JPS6132090B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a pair of work rolls facing each other with a roll gap through which a material passes, as working rolls,
The working roll is a two-high rolling mill that adjusts the roll gap in accordance with the working roll, or a back-up roll that supports the work roll;
The present invention relates to an automatic control method for a four-high rolling mill that adjusts the roll gap in accordance with the operating rolls.

[Conventional technology]

As an automatic control method for this type of rolling mill, the method described in Japanese Patent Publication No. 46-9934 is known. Here, the eccentricity of the working roll is estimated indirectly from the signal about the thickness of the material entering the gap between the rolls and the signal indicating the fluctuation of the rolling load when the material enters the rolling mill, and the eccentricity and length of the roll are estimated. We are trying to eliminate the effect of circularization on the rolled material.

[Problem that the invention seeks to solve]

However, with the above automatic control method, it is necessary to correct errors when the rolling load fluctuation value on the material is large, and error correction is also required for differences in the absolute value of the thickness of the material to be rolled. You can't expect accuracy.

The present invention was made based on the above circumstances, and
The total amount of eccentricity corresponding to the angular position between the working rolls, that is, the variation in the relative distance between the working rolls' chock, is measured in advance at the stage not including the material, and this is stored on the computer side and used in the correction stage during rolling. used as reference data, at least regarding the variation of work roll gap during rolling.
It is an object of the present invention to provide an improved automatic control method for a rolling mill that eliminates the main control factors.

[Means for solving problems]

For this purpose, the present invention uses a pair of work rolls that face each other with a roll gap that allows the material to pass through, or a back-up roll that supports the work rolls as actuating rolls, and adjusts the roll gap in accordance with the actuating rolls. In the measurement step, the working roll is rotated for one beat cycle and its angular position is determined with the relative distance of the chock of the working roll being the total eccentricity and the gap between the work rolls being zero. In the correction step, the total amount of eccentricity is measured and this information is stored on the computer side, and in the correction stage, the material is fed between the work rolls according to the angular position, and the information stored on the computer side is used in the one beat cycle. The work roll gap is corrected using a signal that displays the actual amount of eccentricity based on the actual eccentricity, and the above-mentioned one beat cycle is a process from the measurement reference point of the operating roll until the measurement reference points of both operating rolls coincide again. It is characterized by being set to a length of .

[Effect]

In such a system, it is essentially important that the working rolls are rotated at different angular velocities. The eccentric components of the two working rolls are each periodic, but with slightly different periods due to their different angular velocities. As a result, the change in the total eccentricity component (total eccentricity) has a low periodic beat, and one beat cycle spans many rotations of the working roll. For example, in the beat cycle illustrated in this specification, the smaller working roll (backup roll) rotates one more revolution during one beat cycle than the other working rolls (backup roll). In this one beat cycle,
Changes in the total amount of eccentricity are repeated, so if this is stored on the computer side, constant correction can be made unconditionally in synchronization with the angular position of the operating roll, and fluctuations in the work roll gap due to roll eccentricity can be corrected. , can be removed from the main part of the control factor. As a practical matter, the working rolls are not necessarily of exactly the same diameter, and since there is always some slight angular velocity difference between said working rolls, the synchronization of the change in total eccentricity will occur over many rotations of the working rolls. Therefore, the control method of the present invention is very effective.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings based on a four-high rolling mill, that is, a case where a back-up roll supporting work rolls is used as a working roll.

Now, in FIG. 1, the hydraulically controlled rolling mill comprises a pair of housings 2 each having a window 4. The bottom backup roll 6 is supported at its ends in a chock 8 supported in the window 4. The backup roll 10 is supported at its ends on a movable chock 12 by a pair of hydraulic rams 14 located in the window of the housing, said rams 14 being spaced from the top of the window by a load cell 16. There is. A pair of work rolls 18 and 20 are positioned between backup rolls 6 and 10.

Each hydraulic ram is supplied with hydraulic fluid through a separate servo valve 21 whose operation is controlled by a pair of controllers 22. The movement of the piston 14a of the ram 14 is measured by a separate linear displacement transducer 24. This transducer 24 is connected between the piston and cylinder of each ram.
Each of the backup rolls 6, 10 serves as an actuation roll and has an angular position transducer 26 connected thereto.
Equipped with.

The controls for rolling mill operation are identical on each side of the mill, and on each side of controller 22, a load reference signal on line 28, load cell 1
a rolling load signal on line 30 from 6, optionally a signal from pressure transducer APT, and line 3
receives the signal from the linear displacement transducer on 2.

In addition, the controller receives a signal on line 34 from a summer 36, and an output signal from the controller is provided on line 38 to servo valve 21. The controller has two modes of operation: load control and position control.

Computer 40 receives the signal from angular position transducer 26 and the signal from each of transducers 24 and provides a signal to summer 36 which receives the position reference signal.

The computer uses time sharing so that the actuating roll angular position signals received from transducer 26 are the same on both sides of the mill and are received sequentially and completely independently from both sides of the mill.

The actuating rolls are rotated at normal speed with no material in the roll nip and the work rolls being faced under load. The signal from the linear displacement transducer 24 is fed to the computer, as well as the angular position transducer 2.
A signal from 6 is supplied. This phase, as a measurement phase, typically lasts exactly one beat cycle. However, it is advantageous to extend this by two or more complete beat cycles to increase accuracy and reduce errors arising from other random disturbances.

During the measurement phase, the total eccentricity of the two working rolls is received by the computer, as well as a signal indicating the angular position of the two working rolls. The computer obtains a signal indicating the amount of eccentricity at time intervals corresponding to a constant increase in the angle of rotation in one of the working rolls. In said computer, for each angular position of said actuating roll, the obtained values for said position at each rotation of said actuating roll during a beat cycle are averaged;
Prepare materials that indicate the eccentricity of the operating roll in correspondence with the above angular positions.

In FIG. 2, the upper graph shows the eccentricity X, which is the deviation of the roll radius from the average value of the smaller diameter of the two working rolls (backup rolls) plotted against time, and the lower graph shows: Figure 2 shows the eccentricity Y of other working rolls plotted against time. Here, a mark on the time axis is shown for each complete revolution of the actuating roll for one beat cycle, which in the exaggerated example includes six revolutions of the top actuating roll and six revolutions of the bottom actuating roll. 5 rotations.
X ₁ -X ₆ are the eccentricity values at a single measurement point on the top working roll during continuous rotation. and Y ₁ to _{Y 6} are the corresponding eccentricity values on the bottom working roll. X ₁ ~ X ₆
is a single measuring point on the top working roll X ₁ = X ₂ = X ₃ =…
Since we display the same point on X ₆ , the average value of X ₁ to X ₆ is equal to X ₁ . The lower graph shows six dividing points equally spaced around the bottom working roll.
Shown as Y ₁ to _{Y 6} . Assuming that some average current value, DC level, is removed from Y so that Y actually has an average value of zero, the average value of Y ₁ -Y ₆ becomes substantially zero. This approximation improves as the number of measurement points increases, and it is reasonable to assume that the average value of Y ₁ to _{Y 6} is equal to zero. The computer inputs are on the lower graph at points X ₁ to X ₆ and Y ₁
~Y is the sum of X+Y as shown by ₆ . The above computer has X ₁ + Y ₁ , X ₂ + Y ₂ ,...X ₆ + Y ₆
is programmed to take the average of six readings with an average value of . This average value is equal to the average value of _X1 to _X6 plus the average value of _Y1 to _Y6 .

Since the average value of X ₁ to X ₆ is X ₁ and the average value of Y ₁ to _{Y 6} is zero, the result is X ₁ . For this reason,
The calculator accounts for the value X ₁ for the top-actuating roll.

In this way, if a single measurement point coincidence of the top working roll and the bottom working roll is achieved in one beat cycle, the values of X and Y at a given time division during this time are _e.g. Eccentricity patterns X and Y as values at intermediate dividing points
The total eccentricity difference Y+Y at is completely extracted by the computer.

The eccentricity pattern is then stored in the computer memory as a table of radial deviations at each measurement point, relative to the average of all plotted measurements.

During the correction phase, when the material is rolled between the work rolls, the total eccentricity of the two working rolls is sent from the computer as an analog correction signal and is read out from the computer's memory table in synchronization with the applied working roll rotations. be read. In this case, readings from the table are made at times corresponding to, or equal time intervals around one of the working rolls, the dividing points according to the previous plot. The computer is capable of writing everything in the storage table and provides smooth control output with improved actuation roll rotation in one beat cycle. Furthermore, the computer is controlled by a signal that partially compensates for delays in the hydraulic position control system, and can process information about the work roll gap to exclude the compensation signal from the control factor.

A feature of the invention is that, under appropriate circumstances, the basic system can be expanded and adopted, especially in rolling mills other than reversible hydraulic flat plate rolling mills. Some applications are listed below.

1 During the measurement phase of the mill operation described above, the mill is operated under constant load control and information on the total eccentricity in one beat cycle is obtained from the cylinder displacement transducer. The rolling mill can alternatively be operated under constant position control (ie, a given cylinder extension measured by a displacement transducer), but the work rolls are in contact and loaded. Information on the total amount of eccentricity is measured rolling load fluctuation (supplied from the load cell 16 or pressure transducer to the computer).
derived from. These load variations can be converted into corresponding displacements by the computer, analyzed when using the mill spring constants (known in advance), and stored in memory as described above.

2. In non-reversing rolling mills, especially those with narrow speed ranges, a closed-loop method of eccentricity measurement will give better accuracy. During the other stages following the measurement stage and preceding the correction stage,
The rolling mill is operated under position control and rolling load fluctuations are monitored (as option 1),
At the same time, however, a preliminary eccentricity correction pattern from the computer is sent as a correction to the cylinder position reference. First, the preliminary correction is a
The eccentricity pattern can be pre-measured at zero or b measurement stage. The computer gradually updates the preliminary eccentric pattern using information on rolling load fluctuations. The purpose of this is to reduce load fluctuations to a zero value so that any load fluctuations are considered as signals in the closed loop self-correcting system. Since the rolling mill itself is included in the feedback loop, its errors will be minimal. These errors include gain errors in the input and output of the computer, during hydraulic position control, and motion delays during said position control. Similarly, the assumed value of the rolling mill spring constant may not be important, but
It achieves longer and more accurate measurements, and the ultimately achieved accuracy is difficult to dismiss. The above accuracy is
The rolling mill, which is operated in almost the same conditions as in the measuring phase, is largely guided to those conditions that occur during normal rolling.

3. In rolling mills with sufficiently long transit times, option 2 can be extended to continue the renewal process to the memorized eccentric pattern even after the strip is in the mill. This online update process allows for low changes in eccentricity (e.g. due to roll wear, temperature expansion) to be continuously incorporated into the stored eccentricity pattern.
When the strip is in the rolling mill, the load fluctuation is
This may occur for reasons other than eccentricity (such as variations in the strip introduction gauge). However, these are not synchronized to the rotation of the work roll (backup roll) and, provided the update process is slow enough, will not introduce the slightest error.

4 Apparent eccentricity is also caused by hardness changes on the roll circumference that cause corresponding changes in roll rolling. This apparent eccentricity will depend on the rolling load and probably also on the thickness of the material. To accommodate this, a set of two or more eccentric patterns can be stored in the computer.
A write-up (in terms of load) is made that is used to obtain a real pattern that corresponds to the known operating conditions of the rolling mill. In the case of load, the required set of patterns can be derived by repeating the measurement steps two or more times under different load levels.

5 The scheme can be easily extended to additional use for work roll eccentricity in four-high rolling mills. If the work rolls are driven independently, their diameters must be made different in a certain sense and each must be matched with the angular position measurements mentioned above. The work roll eccentricity measurement thus proceeds in parallel to the back-up roll eccentricity measurement. It would be necessary to incorporate correction provisions into the computer to minimize interactions between the two measurements. If the work rolls are driven in common through a pinion box, only one roll is subjected to angular position measurement and one part of the work roll pattern is
Only one set is memorized (this is the total eccentricity of both work rolls). In addition, in the above embodiment, an automatic control method for a four-high rolling mill that employs a back-up roll as an operating roll is described, but the work roll Of course, the control method of the present invention can also be applied to a two-high rolling mill that uses a work roll as an operating roll.

〔Effect of the invention〕

As described in detail above, the present invention measures the total eccentricity of the actuating roll over one beat cycle, stores this on the computer side, and adjusts the rotation of the actuating roll in the correction stage. The controllability can be improved by synchronously reading out the influence of the variation amount of the work roll gap from the control factor.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view of a four-high rolling mill according to the present invention, and FIG. 2 is a chart schematically showing the eccentricity of operating rolls of the rolling mill. 2...Housing, 4...Window, 6...Backup roll, 8...Chick, 10...Backup roll, 12...Chock, 14...Ram, 14a...Piston, 16...Load cell, 18...Work roll,
20... Work roll, 21... Servo valve, 22
...Controller, 24...Linear displacement transducer, 26...Angular position transducer, 28, 30, 32, 34...Line, 36
...Totalizer, 38...Line, 40...Computer.

Claims (1)

[Claims] 1. A pair of work rolls facing each other with a roll gap for passing the material or a back-up roll supporting the work rolls are used as actuating rolls, and the roll gap is adjusted in accordance with the actuating rolls, in which the chock of the actuating rolls is The relative distance is taken as the total amount of eccentricity, and in the measurement step with the gap between the work rolls set to zero, the working roll is rotated for one beat cycle and the total amount of eccentricity is measured in correspondence with its angular position, This information is stored on the computer side, and in the correction stage, the material is fed between the work rolls in accordance with the above-mentioned angular positions, and a signal is sent that displays the actual amount of eccentricity based on the information stored on the computer side during the above-mentioned 1 beat cycle. The above-mentioned one beat cycle is set to the length from the measurement reference point of the working roll until the measurement reference points of both working rolls coincide again. An automatic control method for a rolling mill characterized by: